"""
难度：简单
用两个栈实现一个队列。队列的声明如下，请实现它的两个函数 appendTail 和 deleteHead ，分别完成在队列尾部插入整数和在队列头部删除整数的功能。(若队列中没有元素，deleteHead 操作返回 -1 )
示例 1：
输入：
["CQueue","appendTail","deleteHead","deleteHead"]
[[],[3],[],[]]
输出：[null,null,3,-1]
示例 2：
输入：
["CQueue","deleteHead","appendTail","appendTail","deleteHead","deleteHead"]
[[],[],[5],[2],[],[]]
输出：[null,-1,null,null,5,2]
提示：
1 <= values <= 10000
最多会对 appendTail、deleteHead 进行 10000 次调用
 
"""

class CQueue:

    def __init__(self):
        self.inStack = []
        self.outStack = []
    def appendTail(self, value: int) -> None:
        self.inStack.append(value)
    def deleteHead(self) -> int:
        if len(self.outStack) ==0 and len(self.inStack) == 0:
            return -1
        if len(self.outStack) ==0:
            while (len(self.inStack) != 0):
                self.outStack.append(self.inStack[-1])
                self.inStack.pop()
        top = self.outStack[-1]
        self.outStack.pop()
        return top
    


# Your CQueue object will be instantiated and called as such:
# obj = CQueue()
# obj.appendTail(value)
# param_2 = obj.deleteHead()